While cannabis is known to lower eye pressure, this review highlights emerging evidence that cannabinoids may also directly protect retinal neurons from death in diseases like glaucoma and diabetic retinopathy.
Read this if you have glaucoma or diabetic eye disease and are curious about how cannabinoids might help beyond lowering eye pressure.
Cannabinoids may protect retinal neurons through neuroprotection, not just IOP reduction
What the researchers found
The connection between cannabis and eye health goes back to the early 1970s when smoking cannabis was found to lower intraocular pressure (IOP). But this review argues that lowering IOP alone is not sufficient to prevent vision loss in diseases like glaucoma.
Glaucoma and diabetic retinopathy are increasingly understood as neurodegenerative diseases characterized by ischemia-induced excitotoxicity and loss of retinal neurons. The review presents evidence that cannabinoids, both endogenous and synthetic, have neuroprotective properties that could directly protect retinal cells from death.
This neuroprotective potential goes beyond IOP reduction and suggests cannabinoids could address the underlying neurodegeneration that drives vision loss, potentially representing a new therapeutic strategy for retinal diseases.
Why it matters
Glaucoma is the second leading cause of blindness worldwide. If cannabinoids can protect retinal neurons beyond simply lowering eye pressure, they could complement existing treatments and potentially prevent vision loss that current therapies cannot address.
The numbers in context
Cannabis has been known to lower IOP since the 1970s. Glaucoma is the second leading cause of blindness globally. Both CB1 and CB2 receptors are present in retinal tissue.
How the study worked
Narrative review of preclinical evidence on the neuroprotective and therapeutic potential of endogenous and synthetic cannabinoids in retinal disease, including glaucoma and diabetic retinopathy.
What this study cannot tell us
Most neuroprotection evidence is preclinical. The review does not quantify the degree of neuroprotection or compare it to existing treatments. Systemic cannabinoid delivery for eye disease raises questions about side effects versus local benefit.
How to read the evidence
Narrative review of primarily preclinical evidence. Compelling theoretical framework but limited clinical evidence for neuroprotection.
When this study was published
Published in 2016. Research on cannabinoid neuroprotection in retinal diseases has continued to advance.
The bigger picture
This review reframes the cannabis-glaucoma discussion from a narrow focus on IOP to a broader neuroprotection paradigm. As retinal diseases are increasingly recognized as neurodegenerative conditions, neuroprotective approaches including cannabinoids deserve more clinical investigation.
Questions still open
- Could topical cannabinoid formulations deliver neuroprotection directly to the retina? Would the neuroprotective effects complement existing IOP-lowering treatments? What cannabinoid formulations would be most suitable for retinal disease?
Common questions
Does cannabis help with glaucoma?
Should glaucoma patients use cannabis?
Read the original research
Endogenous and Synthetic Cannabinoids as Therapeutics in Retinal Disease.
Neural plasticity, 2016, 8373020
Citation
Kokona, Despina; Georgiou, Panagiota-Christina; Kounenidakis, Mihalis; Kiagiadaki, Foteini; Thermos, Kyriaki. (2016). Endogenous and Synthetic Cannabinoids as Therapeutics in Retinal Disease.. Neural plasticity, 2016, 8373020. https://doi.org/10.1155/2016/8373020
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